JPH0823013A - Prober for wafer - Google Patents

Abstract

PURPOSE:To determine whether each integrated circuit is good or bad before it is formed into a chip and is molded and packaged by testing many integrated circuits at a time as they are formed on a wafer. CONSTITUTION:A prober for wafer has a base 10 which has comb-teeth-shaped sections which are formed at the same arrangement pitch as streets between integrated circuits formed on a wafer and a plurality of flexible printed circuit boards 20 which are installed through slots 12 formed between the comb teeth- shaped sections 11 of the prober base 10, and one end of each of which is led out to a test equipment and the other end is located on an upper face of each comb-teeth-shaped section 11 of the prober base 10 through a cushioning member 13. On the surface of the other end of each flexible printed circuit board, a plurality of bumps 26 are formed which can be brought into contact with corresponding pads arranged on a wafer. Each bump 26 is electrically connected to a corresponding conductor of the flexible printed circuit board 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to testing integrated circuits formed on a wafer, and more particularly to a prober for a wafer used for testing a large number of integrated circuits formed on a wafer. .

[0002]

2. Description of the Related Art Semiconductor integrated circuit devices, so-called ICs,
Generally, a chip formed by forming a large number of integrated circuits on a silicon wafer and then cutting the silicon wafer for each integrated circuit is molded or packaged.

Normally, such molded or packaged ICs are subjected to an aging test to eliminate defective ICs. However, if such a molded or packaged IC has to be rejected as a defective product, the cost for molding and packaging is completely wasted, and the final IC product price is high. End up with.

Therefore, before a large number of integrated circuits formed on a wafer are made into chips, a test of these integrated circuits is performed, and the quality of the integrated circuits is checked on the wafer to determine whether the integrated circuits are defective. With regard to the above, it has been considered to save the cost by avoiding the subsequent molding and packaging.

[0005]

However, in order to test the densely arranged integrated circuits on the wafer, the pads of the densely arranged integrated circuits on the wafer are tested. What is needed is a prober with multiple contact terminals that can make accurate and reliable electrical contact. Various kinds of such probers have been developed, but up to now, none of them has been established as a prober that can sufficiently meet the demand.

An object of the present invention is to provide a wafer prober which can sufficiently meet the above-mentioned requirements.

[0007]

According to the present invention, in a wafer prober used for testing a large number of integrated circuits formed on a wafer, an array pitch of streets between arrays of the integrated circuits of the wafer is provided. And a prober base having comb teeth at the same arrangement pitch as that of the prober base and a groove formed between the comb teeth of the prober base, one end of which is pulled out to a test device and the other end of which is the prober base. A plurality of flexible printed circuit boards arranged on the upper surface of each of the comb-shaped parts of the base body via a cushion member, and the flexible printed circuit boards on the surface of the other end of each of the flexible printed circuit boards. A plurality of bumps that can be brought into contact with the pads arranged in the vicinity of the street are provided, and each of the bumps is provided on the flexible printed circuit board. Characterized in that the corresponding conductors are electrically connected.

In one embodiment of the present invention, the probe base is formed of a material having a coefficient of thermal expansion substantially equal to that of the wafer.

In another embodiment of the invention,
In each of the flexible printed circuit boards, the conductor coating on the curved portion extending from the other end disposed on the upper surface of the comb tooth-shaped portion into the groove portion is removed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a schematic partial perspective view partly showing the structure of a wafer prober according to an embodiment of the present invention, and FIG. 2 shows the wafer prober of FIG. 1 for testing. It is a partial schematic front view shown in the state arrange | positioned on a wafer. As shown in FIGS. 1 and 2, the wafer prober 100 of this embodiment includes a prober base 10. The prober substrate 10 may be integrally formed of a material having a coefficient of thermal expansion substantially the same as that of the wafer to be tested, for example, the same silicon material as the wafer. It may be formed of an iron-nickel-based low thermal expansion alloy material commercially available under the trade name "LEX" from Foundry Co., Ltd. in this way,
Matching the coefficient of thermal expansion of the material of the prober substrate 10 with the coefficient of thermal expansion of the wafer to be tested means that both are placed in an atmosphere at a temperature of 125 degrees during the burn-in test. At this time, it is preferable in order to prevent misalignment between the pad on the wafer and the prober.

Comb-tooth-shaped portions 11 are formed on the prober substrate 10 at the same pitch as the streets between the integrated circuits of the wafer to be tested, and between the comb-tooth-shaped portions 11. Has a groove portion 12 formed therein.
Although it is necessary to match the dimensions of the wafer to be tested, for example, the width of the comb tooth-shaped portion 11 is about 2 mm and the width of the groove portion 12 is about 3 mm.

The prober 100 for a wafer is provided through a groove 12 formed between comb-tooth-shaped portions 11 of the prober base 10, one end of which is pulled out to a test device and the other end of which is a comb-tooth-shaped prober base 10. A plurality of flexible printed circuit boards 20 are provided on the upper surface of the portion 11 via a cushion member 13. The other end 21 of each flexible printed circuit board 20 is provided with a comb tooth-shaped portion 1 via a cushion member 13 such as a silicone rubber sheet.
1 is disposed on a corresponding portion of the upper surface of the 1. The cushion member 13 is adhered to the upper surface of the comb-tooth-shaped portion 11 with an appropriate adhesive, and is provided on each flexible printed circuit board.
The other end 21 of is adhered to the cushion member 13 with an appropriate adhesive.

These flexible printed circuit boards 20
Can use, for example, a bumped flexible printed circuit board manufactured by Nippon Mektron Co., Ltd. and marketed through NOK Co., Ltd. This flexible printed circuit board with bumps has a large number of minute through holes formed in an insulating flexible thin base material.
It is like forming solder bumps or via holes in these through holes and forming a circuit conductor pattern for electrically connecting these solder bumps or via holes arbitrarily.

A curved portion 22 extending from the other end 21 of each flexible printed circuit board 20 into each groove 12.
The conductor coating, that is, the insulating base material has been removed by peeling, and in the curved portion 22, the conductor 23 is removed.
Is exposed. In this way, by removing the coating in the curved portion 22, the so-called flying lead method can reduce the springback stress at that portion, so that the degree of influence on the fixing position accuracy of the bump portion 26 can be reduced. Less.

Next, each comb tooth-shaped portion 11 of the prober base 10 is formed.
Each flexible printed circuit board 2 disposed on the upper surface of the
The detailed configuration of the other end 21 of 0 will be described. Figure 1
FIG. 4 is an enlarged sectional view of the other end 21 of one flexible printed circuit board 20, and FIG. 4 is an enlarged partial plan view of the other end 21. As shown in FIGS. 3 and 4, the other end 21 of each flexible printed circuit board 20 is
In, the bumps 26 are connected to the end portions of the plurality of conductors 23 arranged between the insulating base materials 24. These bumps 26 are composed of hemispherical portions at the tips of the columnar objects formed through the through holes 25 formed in the base material 24.

Each conductor 23 of the flexible printed circuit board 20 is, for example, a copper wiring having a width of 50 μ, and the arrangement pitch is also 50 μ. The pillars that give the bumps 26 are
It is formed of, for example, nickel so as to be connected to the tip of each conductor 23 through the through hole 25, and the hemispherical portion of the tip has a size of, for example, 50 μφ and is projected from the surface of the base material 24. Has been. Gold plating may be applied to the surface of the hemisphere that gives the bump 26.

FIG. 5 is a plan view showing an example of a wafer to which the wafer prober of the present invention is applied. On this wafer 200, for example, 384 integrated circuits 201 are formed. The spaces 202 between the arrays of these integrated circuits 201 are called streets. Each integrated circuit 201 has a total of 38 pads 203, 19 on each side.
(Not shown in FIG. 5) are provided. Figure 6
Is an integrated circuit 201 formed on the wafer 200 of FIG.
FIG. 3 is a partial plan view showing only one part of the above in an enlarged manner and omitting a corresponding part. As best shown in FIG. 6, the streets 20 on each side of each integrated circuit 201.
Nineteen (five of which are shown in FIG. 6) pads 203 are formed in the vicinity of two so as to be exposed on the surface of the wafer 200.

Each pad 203 is electrically connected to each circuit terminal of the corresponding integrated circuit 201 formed on the wafer 200. For example, each pad 203 is 80 μm square, and as shown in FIG. Center line 20 of street 202
It is arranged on a line that is spaced 200 μm inward from the No. 4. Therefore, in the case of such a wafer 200, 400 .mu.
That is, the pads 203 are arranged in two rows at intervals of. The distance between the pads 203 in each row is, for example, 300 μ. When the wafer prober 100 is used for such a wafer 200, the other end 21 of each flexible printed circuit board 20 is used.
There are 19 bumps 26 in one row and two bumps 26 are provided in two rows. The spacing between the rows is 400 μ, and the spacing between the bumps in each row is 300 μ.

When the wafer 200 is tested by using the above-described wafer prober 100 of the present invention, as shown in FIG. The wafer prober 100 is mounted on the test base 1 and the wafer 200 is mounted on the test base 1.
Are aligned with respect to each other so that they are pressed into contact with each other.
At this time, the bumps 26 arranged in two rows on the other end 21 of each flexible printed circuit board 20 are mounted on the wafer 200.
It is pressed into contact with each corresponding pad 203 above. Therefore, the integrated circuit 201 formed on the wafer 200
Each of the pads 203 of FIG. 1 will be electrically drawn out to the external test equipment (not shown) through each conductor 23 of the flexible printed circuit board 20 via the bumps 26 respectively contacted therewith.

At this time, the comb-shaped portion 1 of the prober base 10
1 according to each bump 26 pad 20 of the wafer 200
3 against all the pads 2 even if the wafer 200 has a general swell or a local distortion.
The bump 26 can be reliably brought into contact with 03. Further, since the cushion member 13 is provided between the other end 21 of each flexible printed circuit board 20 on which the bumps 26 are arranged and the upper surface of each comb-tooth-shaped portion 11 of the prober base 10, the bumps 26 are provided. Even if there is some variation in the height of the bumps, these variations can be compensated by cushioning the cushion member 13, and a more reliable contact state between each pad 203 and each bump 26 can be maintained.

In the above-described embodiment, the flexible printed circuit board 20 is one flexible printed circuit board on which one of the plurality of integrated circuits 201 formed on the wafer 200 is applied. The present invention is not limited to this, and for example, one flexible printed circuit board may be used for two or three integrated circuits.

[0023]

According to the wafer prober of the present invention,
Since a large number of integrated circuits formed on a wafer can be tested at one time, the quality of each integrated circuit can be determined before molding and packaging into chips. Therefore, it is possible to eliminate waste of molding or packaging the originally defective integrated circuit.

Since the comb-tooth-shaped portion is formed on the prober base and the bump is arranged on the portion through the cushion member,
Even if the wafer has undulations or distortion, or even if the height of the bumps varies, it is possible to always reliably make electrical contact with each pad on the wafer.

[Brief description of drawings]

FIG. 1 is a schematic partial perspective view partially showing the structure of a wafer prober as an embodiment of the present invention.

2 is a partial schematic front view showing the wafer prober of FIG. 1 arranged on a wafer for testing. FIG.

3 is an enlarged cross-sectional view of the other end of one flexible printed circuit board used in the wafer prober of FIG.

FIG. 4 is an enlarged partial plan view of the other end of the flexible printed circuit board shown in FIG.

FIG. 5 is a plan view showing an example of a wafer to which the wafer prober of the present invention is applied.

6 is a partial plan view showing, on an enlarged scale, only one portion of the integrated circuit formed on the wafer of FIG. 5 and omitting a corresponding portion.

[Explanation of symbols]

 1 Test Base 10 Prober Base 11 Comb Tooth 12 Groove 13 Cushion Member 20 Flexible Printed Circuit Board 21 Other End 22 Curved Part 23 Conductor 24 Base Material 25 Through Hole 26 Bump 100 Wafer Prober 200 Wafer 201 Integrated Circuit 202 Street 203 pad

Claims (3)

[Claims] 1. A wafer prober for use in testing a large number of integrated circuits formed on a wafer.
Arranged through a prober base having comb-tooth-shaped portions at the same pitch as the street pitch between the arrays of the integrated circuits on the wafer, and a groove formed between the comb-tooth-shaped portions of the prober base. A flexible printed circuit board having a plurality of flexible printed circuit boards, one end of which is pulled out to a test device and the other end of which is disposed on the upper surface of each comb-tooth-shaped portion of the prober base via cushion members. On the surface of the other end of each of the substrates, a plurality of bumps capable of contacting the pads arranged near the streets of the wafer are provided, and each of the bumps has a flexible print. A prober for a wafer, which is electrically connected to each corresponding conductor of a circuit board. 2. The prober for a wafer according to claim 1, wherein the probe base is made of a material having a coefficient of thermal expansion substantially equal to that of the wafer. 3. The flexible printed circuit board according to claim 1, wherein the conductor coating on the curved portion extending from the other end disposed on the upper surface of the comb-shaped portion into the groove is removed. 2. A wafer prober according to 2.